Circulating pump structure and the like



y 4 H. c. SWAY 2,677,383

CIRCULATING PUMP STRUCTURE AND THE LIKE Original Filgd Feb. 9, 1949 Invehtor'. Henry CSWay,

His Attorney.

Patentecl May 4, 1954 TED STATES TENT OFFICE Henry C. Sway,

Bridgeport, Conn, assignor to General Electric Company, a corporation of New York Original application February 9, 1949, Serial No.

75,466, now Patent 3 Claims. 1

This application is a division of my application Serial No. 75,466, filed February 9, 1949, now Patent No. 2,654,377, issued October 6, 1953.

In the operation of dishwashing machines and the like wherein a relatively small quantity of water is continuously circulated or splashed about a tub by the relatively high speed rotation of an impeller, difficulty has been experienced with an undesirable surging and pulsing in the water flow, especially when the dish load was light. A dishwasher impeller has usually a high water pumping capacity, a capacity for example of the order of 50 gallons per minute, and there may be but one gallon of water in the tub. The water content of the tub is therefore thrown up by the impeller almost at once and returns cyclically to the impeller. As a result the motor may be subjected to successively high load peaks and intermediate light load valleys.

The object of the present invention is to provide an improved pump structure wherein the flow of Water to the pump and the discharge of water from it is ironed out and made more uniform whereby undesirable surging and pulsing is eliminated, and for a consideration of what I believe to be novel and my invention, attention is directed to the following specification and to the claims appended thereto.

According to my invention, I overcome the above difficulties by providing a metering ring or wall which surrounds the impeller and is arranged to provide an orifice, preferably an annular orifice, through which water is fed to the impeller whereby the flow of water to the impeland hence discharge from it is made fairly uniform under all conditions of operation.

In the drawing, the figure is a sectional view of a dishwasher having a circulating pump embodying the invention.

Referring to the drawing, l indicates the tub of a dishwasher having a cone-shaped or downwardly tapered bottom wall 2 which defines a well or sump 3. In well 3 is a pump impeller comprising a hub A and blades 5 carried by the shaft of an electric motor 6 which in turn is supported on bottom wall 2. Hub 4 and blades 5 may be molded from a suitable rubber compound or plastic material and the blades are shaped to provide a sharp angle of attack as is known in dishwashing machines. The water supply conduit is indicated at 7, the drain conduit at 8, the dish racks at 9, and the drain pump at H).

The structure so far described forms no part of my present invention. It is to be taken as No. 6, 1953. Divided and 1952, Serial No. 287,148

2,654,377, dated October this application May 10,

2 typical of any suitable dishwasher machine structure.

According to my invention, I regulate flow of water to the impeller and thus minimize the effect of the cyclic condition referred to above by utilizing a metering ring or wall I2 which is supported by a suitable wire standard l3. The ring or wall 52 extends to or slightly above the static water level of the tub which level is indicated at L. As shown in the drawing the bottom of ring 52 is suificiently above the adjacent bottom wall of the tub to provide a relatively low or narrow circumferential orifice [4 through which the water flows to the impeller. The ring, therefore, meters water flowing to the impeller and prevents any substantial amount reaching the impeller above the base thereof. The metering ring effectively reduces the surging which occurs if the water is allowed to circulate freely into the impeller. It will be noted that the ring fits relatively closely about the impeller at the low point of the bottom of the tub. Thus after the quantity of water within the ring has been thrown upward by the impeller, water flows to the impeller substantially only through the orifice I i. A metered flow of water to the base of the impeller is thereby provided. The metering ring effectively reduces the critical eifect of the quantity of water within the tub; for example. it has been demonstrated that the quantity of water may be doubled, for instance where the normal amount is 1 gallon increased to 2 gallons, without overloading the motor.

My invention has the advantage that not only does it overcome the difiiculties referred to above but also the advantage that it is simple in structure and may be provided at relatively low cost.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A dishwashing machine or the like comprising a tub having a bottom sloping to a low point, an impeller within said tub at the low point thereof, said impeller having an upwardly extending hub, means for introducing a predetermined quantity of washing fluid into said tub, said quantity assuming a static level substantial- 1y midway up the impeller hub, and a wall disposed about said impeller, said wall extending upwardly at least to the said static water level and being spaced from the bottom wall of the tub about the impeller sufiiciently to provide a relatively narrow orifice controlling flow of fluid to the base of the impeller, said orifice having a fluid fiow capacity suinciently less than the fluid pumping capacity of said impeller that a substantially uniform rate of flow through said orifice is maintained during washing operations.

2. A dishwashing machine or the like comprising a tub having a bottom sloping to a low point, an impeller within said tub at the low point thereof, said impeller having an elongate hub extending upwardly into said tub, means for introducing water into said tub to a normal static level substantially midway up the impeller hub, and a wall disposed about said impeller and extending from a point above the bottom of the tub to the static water level of the tub, the bottom of said tub and the lower edge of said wall forming an orifice limiting the rate of flow therethrough to a value less than the pumping capacity of said impeller.

3. A dishwashing machine or the like comprising a tub, an impeller therein, said impeller including an elongate hub extending upwardly from the bottom of the tub, means for introducing water into the tub to establish a predetermined static water level which is intermediate the hub length, and a wall disposed relatively closely about said impeller in fixed relation therewith, said wall extending upwardly to at least said static water level and being spaced above the bottom of the tub sufficiently to pro vide an orifice discharging beneath said impeller, said orifice having a fluid flow capacity less than the fluid pumping capacity of said impeller, whereby a substantially uniform rate of fluid circulation is maintained during washing operations.

References Cited in the file of this patent UNITED STATES PATENTS Number 

